1. Field of the Invention
The present invention relates to a hard candy with a relatively-high moisture and hardness, and more particularly to a hard candy enriched with trehalose and having a relatively-high moisture and hardness, and to a process of the same.
2. Description of the Prior Art
As disclosed in Japanese Patent Kokoku Nos. 34,788/82 and 50,698/83, hard candies are generally prepared by condensing aqueous saccharide solutions under heating conditions into those with a moisture content of two w/w % or lower (the wording xe2x80x9cw/w %xe2x80x9d is abbreviated as xe2x80x9c%xe2x80x9d, unless specified otherwise), and in an usual manner cooling and shaping the concentrate. The aqueous saccharide solutions need a relatively-large amount of energy to be concentrated into such concentrates with a relatively-low moisture. The solutions have a relatively-high viscosity and need a relatively-high level handling. Thus, if the saccharide solutions should not necessarily be condensed to such a low-level of moisture, the energy consumption can be lowered, and the process of hard candies can be easily and simply improved.
However, it is generally said that when incompletely condensed as to show a relatively-high moisture content, particularly to a high-moisture content of over about 3.5%, hard candies may cause the following unfavorable problems: The hard candies become less hardened and become impossible of cooling and shaping, absorb moisture, change on shape, crystallize to show opaque, and cause adhesion and stickiness to the teeth.
Recently, trehalose or xcex1,xcex1-trehalose, a disaccharide as a food material, has become widely used. Trehalose has characteristic features of non-reducibility, satisfactory pH- and thermal-stabilities, mild and high-quality sweetness, relatively-low cariogenicity as a sweetener, and the use of an energy-source for living bodies. Therefore, it has been expected for establishing hard candies using such a useful trehalose characterized by the above satisfactory features. However, it has been known that trehalose has a serious demerit of easy crystallization when processed into hard candies. For example, Japanese Patent Kokai No. 256,694/96 discloses in the paragraph [0013] as follow: The percentage of trehalose in the material saccharides is preferably in the range of 0.5-60% by weight; it is not preferable at below the lower limit of 0.5% because the present effect will not be expected, and it is not preferable at over the upper limit of 60% because trehalose may crystallize during the processing of hard candies. In Example 1 of the above Japanese Patent Kokai, hard candies are produced by adjusting the trehalose content to 10% to the total material saccharides and using sugar and starch-based syrups as the resting 90% of starch hydrolysates. Japanese Patent Kokai No. 238,642/97 discloses in the paragraph [0015] as follow: It was found that the sole use of trehalose as a material for confectioneries such as candies is impossible due to the property of trehalose in terms of its way of crystallization. Example 1 of the Japanese Patent Kokai discloses a candy, prepared by providing 700 g maltitol with a purity of 95% and 300 g trehalose with a purity of 99.8%, adding water to the saccharides into a 70% composition for confectioneries, condensing the composition until heated to 180xc2x0 C., and pouring the concentrate into a depositor to make a hard candy.
It was found that such a hard candy has the following defects: It is too low the proportion of trehalose to sufficiently exert the characteristic features of trehalose, and more particularly a hard candy, as disclosed in Japanese Patent Kokai No. 238,642/97, prepared by condensing an aqueous trehalose solution up to a high temperature of 180xc2x0 C., is poor in the preservation stability under the above conditions and susceptible to crystallization of trehalose and to lack of transparency. Examples of candies, processed with a large amount of trehalose, are those disclosed in Examples B-10 and B-11 in Japanese Patent Kokai No. 336,363/96. These candies are, however, not hard ones but soft ones with a relatively-low hardness, fine trehalose crystals, and poor transparency.
The present invention relates to a novel hard candy which has a relatively-high moisture and hardness, as well as a satisfactory stability, and which does not need to be concentrated up to give a relatively-low moisture content; and more particularly relates to a hard candy enriched with trehalose and having the aforesaid advantageous features, a relatively-high moisture and hardness, and a satisfactory stability; and to a process of the same.
To overcome the above object, the present inventors continued studying on the use of saccharide solutions, and more particularly on the use of aqueous trehalose solutions. As a result, they unexpectedly found that a hard candy, enriched with trehalose and having a relatively-high moisture, hardness, and stability, is obtainable by concentrating under heating conditions an aqueous trehalose solution with a relatively-low trehalose concentration, which does not become saturated at around 70xc2x0 C. with respect to trehalose, to make a moisture content from about 3.5% to about 10% as smooth as possible. Thus, the present inventors accomplished this invention.
To solve the above object, the present invention provides a hard candy with a relatively-high moisture, hardness, and stability by condensing aqueous trehalose solutions to give moisture contents from about 3.5% to about 10%, and preferably those from about 4% to less than 10%.
The trehalose, alias a,a-trehalose, used in the present invention includes any types of trehaloses as long as they can be used for producing the present hard candy, independently of their origins and properties. Trehaloses from different origins, for example, one from yeasts obtained by extraction as disclosed in Japanese Patent Kokai No. 246,097/95, one from maltose by the method with phosphorylases as disclosed in Japanese Patent Kokai No. 216,695/83, and those from starches by the saccharification method with enzymes as disclosed in Japanese Patent Kokai Nos. 170,977/95 and 213,283/95 can be arbitrarily used.
Commercially available high-purity hydrous crystalline trehalose and high-purity anhydrous crystalline trehalose can be appropriately used. For example, xe2x80x9cTREHAOSE(copyright)xe2x80x9d, a high-purity hydrous crystalline trehalose commercialized by Hayashibara Shoji, Inc., Okayama, Japan, can be also used arbitrarily.
Trehalose alone or in combination with other saccharides in an amount that does not spoil the properties of trehalose can be used as the saccharides in the present invention. Usually, the recommendable proportion of trehalose to the total sugars is over 60%, and preferably 65% or higher, on a dry solid basis (d.s.b.).
Examples of the saccharides suitably used in the present invention are one or more saccharides such as glucose, fructose, isomerized sugars, honey, maple syrup, maltose, isomaltose, sucrose, lactose, paratinose, neotrehalose, maltotriose, panose, raffinose, glucosyl trehalose, lactosucrose, isomaltooligosaccharides, soybean oligosaccharides, fructooligosaccharides, oligosaccharides with lactose and fructose, starch hydrolysates, and cyclodextrins; and sugar alcohols such as erythritol, xylitol, sorbitol, maltitol, lactitol, palatinate, and hydrogenated starch hydrolysates. The proportion of the saccharides to the total sugars can be chosen from those less than 40%, and preferably not higher than 35%, d.s.b., depending on use.
According to the present invention, saccharides, which could not have been used in conventional hard candies, such as fructose, isomerized sugars, honey, maple syrup, xylitol, and sorbitol can be used and easily processed into hard candies with a relatively-high moisture, hardness, and stability.
In the process for producing the present hard candy, the aqueous trehalose solutions preferably used in the present invention include those which have a relatively-low concentration of trehalose and do not reach to the saturation level at around 70xc2x0 C., more preferably those with a trehalose concentration of less than 70%, and more preferably those with a trehalose concentration of about 60% or lower. These aqueous saccharide solutions can be generally concentrated to give a moisture content of 10% or lower, preferably those from about 3.5% to about 10%, more preferably those from about 4% or higher to less than about 10% for effectively eliciting the properties of trehalose, and more preferably those from about 5% or higher to less than about 10%. The methods for shaping the resulting concentrates include the systems of depositing, stumping and cutting, which are appropriately selected on demand.
The present hard candy, with a relatively-high moisture and hardness and enriched with trehalose, has a relatively-high thermal- and preservation-stabilities due to the property of trehalose per se, and has a relatively-lower temperature needed for condensation as to be enough for shortening the condensation time. The following substances with a poor thermal stability can be incorporated into the present hard candy without substantially deteriorating them into a highly-transparent hard candy: Taste-imparting agents such as highly-sweetened sweeteners including monosaccharides, amino acids/nucleic acid seasonings, and steviol glycosides/peptide sweeteners; natural pigments such as chlorophylls, carotenoids, proanthocyanidins, i.e. anthocyanins, and flavonoids; other natural pigments from flowers, vegetables, fruits, herbs, medicinal plants, microorganisms, and insects; natural flavors, vitamins, biological active substances, and medical ingredients. The hard candy thus obtained has a satisfactory shelf-life and is superior in properties in view of its taste preference, nutritional value, and health value.
Thus, one or more of adequate edible food materials such as nutritives, preferences, biological active substances, medical ingredients, and additives can be used and incorporated into the present hard candy as long as they do not spoil the property of the present hard candy. Solids such as fried fruits, seeds, crystallized saccharides, granules of vitamins, and other types of hard candies can be formulated by injecting into the present transparent hard candy to be seen through.
The nutritives appropriately used in the present invention include ingredients which are or may be defective in hard candies, energy-supplementing ingredients, and tonic ingredients; proteins, amino acids, lipids, vitamins, and minerals, as well as agricultural products such as vegetables, fruits, seeds, and processed products thereof; and products of fisheries and livestocks. The processed foods arbitrarily used in the present invention are, for example, the above agricultural products, fisheries, and livestocks being fragmented, pulverized, grounded, pressed, dried, and powdered; and others such as extracts, juices, purees, and concentrates of the above agricultural products. If necessary, seasoned and processed products such as pickles and dried foods can be arbitrarily used intact or those in a pulverized or powdered form after processed by heating or cooked by heating.
The agricultural products arbitrarily used in the present invention are as follow: Rootcrops such as a carrot, Indian lotus, onion, edible burdock, radish, taro, yam, sweet potato, and potato; vegetables such as a lettuce, wild chicory, cabbages including Chinese cabbage, kale, Jew""s marrow, ashitaba (a plant of Oenanthe javanica), spinach, tsuyumurasaki (a kind of vegetable), komatsuna (a kind of Chinese cabbage), nozawana (a kind of turnip), garland chrysanthemum, chingensai (a Chinese vegetable), and turnip; vegetable fruits such as an okura, cauliflower, broccoli, egg plant, tomato, cucumber, pumpkin, zucchini, sweet pepper, field pea, garden bean, and green soybean; vegetables including sprouts such as an alfalfa, soybean sprout, and mung bean sprout; mushrooms such as a Japanese mushroom, velvet-stemmed agaric, and oyster mushroom; seaweeds such as a hijiki (a kind of brown algae), wakame seaweed, and tang; citrus fruits such as a lemon, yuzu (a Chinese lemon), sudachi (a kind of citrus fruit), zabon (shaddock), and kumquat; fruits such as a banana, pineapple, Chinese gooseberry, strawberry, hawthorn, blueberry, grape, peach, apple, pear, and Japanese chestnut; and seeds such as a Job""s tear, buckwheat, sesame, rice, barley, wheat, corn, broad bean, soybean, peanut, walnut, pine nut, and other seeds and germs.
The preferences used in the present invention include a tea, green tea, coffee, cocoa, coca, herb, and medicinal plant; Examples of the herbs used in the present invention are a garlic, ginger, Japanese horseradish, mustard, parsley, Chinese parsley, green and red perilla (a beefsteak plant), Chinese chive, Welsh onion, celery, water dropwort, cresson, red pepper, Japanese pepper, pepper, rosemary, mint, mugwort, plantain, bad-smelling perennial plant of the family Saururaceae, Cassia obtusifolia, Japanese green gentian, aloe, licorice, turmeric, Japanese indigo plant, Pfaffia, loquat leaf, field horsetail, bamboo leaf, Japanese apricot, green tea, fresh leaf of burley, buckwheat leaf, ginkgo leaf, tochu-cha (a Chinese gutta percha leave), oobanasarusuberi (a plant of the family Lythrum), Aspalathus linearis, and Gymnema sylvestre. The biological active substances and medicinal ingredients used in the present invention include vitamins, hormones, saponins, antibiotics, antipyretic/sedative agents, fungicides, snapping turtle extracts, oyster meat extracts, ginseng extracts, nandin extracts, Chinese quince extracts, chlorella extracts, aloe extracts, propolis extracts, glycosyl hesperidin, and glycosyl rutin. Examples of the additives suitably used in the present invention are sweeteners, viscosity-imparting agents, stabilizers, antioxidants, acids, seasonings, emulsifiers, enhancers, colors, and flavors.
In spite of a relatively-high moisture content, the present hard candy thus obtained is one with a relatively-high product value because it has a relatively-high hardness and transparency, does not substantially stick to the teeth, has a saccharide part enriched with trehalose but free of coloration; stably encloses unstable substances per se such as natural pigments and flavors, vitamins, biologically active substances, and medical ingredients; has a satisfactory taste and flavor, and has an extremely-agreeable preservation-stability free of or substantially free of changing on the above properties. Unlike conventional hard candies made mainly of sugar and starch-based syrup, the present hard candy is a novel hard candy that does not stimulate the teeth of persons with hyperesthesia.
The present hard candy keeps a relatively-high hardness even when condensed at a relatively-high temperature; it is produced with a lesser energy consumption needed for the condensation, and it is easily handled even in a condensed form and effectively processed in a relatively-high productivity and yield.
The preferred embodiments according to the present invention are described below in detail:
Experiment 1
Comparison of Thermal Stability of Aqueous Saccharide Solutions
Crystalline glucose anhydride, crystalline maltose monohydrate, crystalline sucrose anhydride, crystalline maltitol anhydride, and crystalline trehalose dihydrate in a reagent grade were used as saccharides in this experiment. These saccharides were respectively mixed with 50 mM acetate buffer (pH 4.0) and 50 mM phosphate buffer (pH 7.0) to give a concentration of 70%, d.s.b., and dissolved by heating into aqueous saccharide solutions for testing. About 150 ml of each saccharide solution was placed in a 300-ml beaker, covered with aluminum foil, treated by heating with an autoclave at 120xc2x0 C. for 30 min, cooled to 80xc2x0 C., and examined for the color of the heated saccharide solutions. The degree of coloration of the heated saccharide solutions was expressed with the symbols xe2x80x9cxe2x88x92xe2x80x9d, xe2x80x9c+xe2x80x9d, xe2x80x9c++xe2x80x9d, xe2x80x9c+++xe2x80x9d, and xe2x80x9c++++xe2x80x9d, representing colorless, pale yellow, yellow, yellow brown, and brown, respectively.
The results are in Table 1.
As evident from Table 1, trehalose and maltitol as a sugar alcohol did not color at both pHs of 4.0 and 7.0, and showed a satisfactory thermal stability. It was found that glucose and maltose were relatively poor in thermal stability, and they were more susceptible to coloration at around neutral pHs, while sucrose was poor in thermal stability at acid pHs.
Experiment 2
Change by Heating on Aqueous High-concentrated Trehalose Solution
Crystalline trehalose dihydrate was placed in 300-ml beakers, and mixed with and dissolved by heating in water into pH-uncontrolled 50%, 60% and 70% aqueous trehalose solutions, d.s.b. The beakers were placed on an electric heater and heated while measuring the temperature of the solutions with xe2x80x9cMODEL SK-1250MCxe2x80x9d, a digital thermometer commercialized by Sato Keiryoki Mfg., Co., Ltd., Tokyo, Japan. It was revealed that the solutions began to boiling at about 106xc2x0 C., and when heated continuously, the solution with 70% trehalose as an initial concentration started to crystallize trehalose at about 115xc2x0 C., and then lost its free-flowing ability and resulted in solidification. The aqueous trehalose solutions with 50% and 60% trehalose unexpectedly did not crystallize at about 115xc2x0 C., and still retained their free-flowing ability even at a temperature of over 165xc2x0 C., resulting in a novel finding that the aqueous trehalose solutions can be used intact as a concentrating solution for hard candies. Although the reason was uncertain, it can be estimated that a slight amount of trehalose crystal exists in the aqueous trehalose solutions by some reasons, and the crystal acts as a core seed for initiating the crystallization.
Experiment 3
Influence of the Types of Aqueous Saccharide Solutions and the Concentration Temperatures on Hard Candy
Crystalline sucrose anhydride, crystalline maltitol anhydride, and crystalline trehalose dihydrate were used as saccharides.
Each saccharide was placed in a pan and mixed with water. The resulting mixtures were heated into 50% aqueous saccharide solutions, concentrated until heated to temperatures from 115xc2x0 C. to 165xc2x0 C., while the aqueous solutions were sampled and placed in a depositor at an interval of 10xc2x0 C. increase of the solutions"" temperature, and cooled to ambient temperature into candy samples with a size of 2 cm length, 1.5 cm wide, and 0.5 cm thick. Using the samples on the day of processed, they were measured for the levels of moisture, hardness, transparency, coloration, and stickiness to the teeth.
Fresh preparations of the same candy samples were placed in polyethylene bags with about 40xcexc thick, allowed to stand at about 25xc2x0 C. for five days, and observed on transparency and stickiness to the teeth. The moisture content was measured in a usual manner by the method using diatomaceous earth. Using xe2x80x9cFUDOH RHEO METER NRM-2010J-CWxe2x80x9d, a rheometer commercialized by Rheotech Co., Ltd., Tokyo, Japan; and a cylinder, about 3 mm in diameter, as an adaptor, the hardness was measured in a manner that a sample stage was elevated at a programmed rate of 2 cm/min to the cylinder, and measuring the intrusion strength (kg) when the cylinder inserted into the sample.
The coloration was evaluated by macroscopically observing the samples based on the same criterion as in Experiment 1. The transparency was studied by macroscopically observing the degree of transparency of the samples. The results of observation were graded into three ranks: High, low, and unobserved. The stickiness of samples to the teeth was examined based on the degree of stickiness to the teeth when bitten in the mouth, and the results were expressed by two grades of found, and not found.
The results are in Table 2.
As evident from Table 2, it was found that, comparing with the aqueous solutions of sucrose and maltitol, the aqueous trehalose solutions keep a relatively-high moisture-retaining ability from 125xc2x0 C. to about 165xc2x0 C. under normal atmospheric pressure, and can be processed into hard candies with a relatively-high moisture, hardness, and transparency. It was also found that, unlike the hard candies processed with aqueous solutions of sucrose and maltitol, the hard candies processed with the aqueous trehalose solution retained a satisfactory stability with a lesser change on standing even when stored at ambient temperature. For the condensations with a reduced moisture content, obtained by condensing the aqueous trehalose solution at 155xc2x0 C. or 165xc2x0 C., the one at 155xc2x0 C. slightly crystallized, and the other at 165xc2x0 C. strongly crystallized and lost its transparency.
The above feature of trehalose was more exerted at lower temperatures in the range of from 125xc2x0 C. to 155xc2x0 C., and preferably in the range of from 125xc2x0 C. to below 155xc2x0 C., meaning that the hard candies processed by condensing at temperatures of from 125xc2x0 C. to below 155xc2x0 C. have a clearly higher moisture content of from about 3.5% to about 10% than those prepared with sucrose and maltitol, and preferably a moisture content of from about 4% to less than about 10%, and most preferably a moisture content of from about 5% to less than about 10%. These hard candies have a relatively-high hardness in spite of their relatively-high moisture, and have a satisfactory coloration, insubstantial stickiness to the teeth, lesser change on standing, and satisfactory stability.
Experiment 4
Influence of the Presence of Other Saccharides on Hard Candy Containing Trehalose
Crystalline trehalose dihydrate was placed in a pan and mixed with water, and the mixture was heated into an about 50% aqueous trehalose solution. To the aqueous trehalose solution was added other saccharide of crystalline maltose monohydrate, crystalline sucrose anhydride, or crystalline maltitol anhydride to give a respective concentration of 30%, 60%, 65% or 80%, followed by dissolving the mixture by heating and adding a matcha (a powdered tea) in and to the resulting solution in an amount of 0.2% to the total contents. The solutions thus obtained were concentrated by boiling until heated to 145xc2x0 C., and then poured into a depositor similarly as in Experiment 3, and cooled to ambient temperature to obtain a sample candy with the similar shape as the product in Experiment 3. Using the candy on the day processed, it was measured for hardness and examined on transparency, tint of matcha, and stickiness to the teeth according to the method in Experiment 3.
Similarly as in Experiment 3, fresh preparations of the same sample were placed in polyethylene bags, allowed to stand at 25xc2x0 C. for five days for observing transparency and stickiness to the teeth. The results are in table 3.
As evident from the results in Table 3, it was found that the hard candies with a trehalose content of over 60% to the total sugars, d.s.b., particularly, the hard candies with a trehalose content of at least 65%, d.s.b., well exert the properties of the hard candies of trehalose, prepared using a relatively-low concentration temperature of 145xc2x0 C.; the hard candies have a relatively-high hardness and transparency, substantially do not have a stickiness to the teeth, well retain the vivid tint of matcha per se, have a satisfactory matcha taste, exert features suitable for hard candies such as a high shelf-life, and have a high product-value. It was also found that the hard candy with a lower trehalose content of 30% may not be expected for a sufficient hardness, tends to lose the tint of matcha per se, causes stickiness to the teeth, and has other defect of being susceptible to change on standing.